CX254
120V Model
The amplifier shall contain all solid-state circuitry, using complementary silicon output devices. The amplifier shall operate from 50–60 Hz AC power and shall draw 1125 VA or less when driven with random program material at 1/8 of rated power into 4-ohm loads. The amplifier shall have a 320-C19 16A IEC mains connector and shall be equipped with a removable power cord having a standard NEMA AC plug. The amplifier shall operate safely from a 15A 120V AC outlet, and shall comply with FCC part 15 Class B requirements.
The amplifier shall have internal heat sinks cooled by forced air, driven by a 24-volt DC fan whose speed shall vary in response to heat sink temperatures to minimize acoustic noise. The fan's speed shall be controlled by a drive voltage ranging from approximately 9 volts when cool to approximately 24 volts when at the upper ranges of its operating temperature. Air flow shall be from rear to front to avoid temperature rise inside equipment racks; rack mounting of multiple amplifiers shall be possible without clearance for ventilation. The amplifier shall be capable of continuous operation at 1/3 of rated power into 4-ohm loads, in ambient temperatures up to 104° F (40° C).
The amplifier shall contain four independent amplifier channels powered by a low-impedance switching power supply. All amplifier protection systems shall be synchronized and self-resetting upon removal of fault. Each channel shall have circuitry to protect against short circuits or mismatched loads. Each channel shall independently monitor heat sink temperature and shall trigger fan speed boost, and if necessary, signal muting to prevent excessive temperature rise. Both channels shall have synchronized on-off muting, acting for three seconds after turn-on, and within ¼ second after turn-off or loss of AC power. Each channel shall have DC fault protection for the load, consisting of a shutdown of the power supply. Each channel shall have an independent and defeatable clip limiter and a 12 dB per octave high-pass filter. The corner frequency of the filter shall be selectable between 33 Hz and 75 Hz.
The front panel shall contain these features: an AC power switch; LED status indicators for power (green), bridged mono (yellow), and parallel inputs (yellow); independent LED output metering indicators for each channel for signal present or –30 dB (green), -20 dB (green), -10 dB (green), and clip (red); and a recessed, detented gain control for each channel with 21 attenuation settings. From 0 to 14 dB, the attenuation steps shall be 1-dB increments. The labeled attenuation settings shall be 0, 2, 4, 6, 8, 10, 12, 14, 18, 24, and ∞ dB. The 0 dB attenuation settings shall also be labeled with the amplifier’s equivalent voltage gain in dB. A removable security panel shall be provided for covering and preventing unauthorized access to the gain controls, when needed.
The output connectors for all channels shall be barrier strips located on the rear panel, with screw terminals and a safety shroud. One barrier strip shall be used for channels 1 and 2, and the other for channels 3 and 4. The terminals shall be arranged to facilitate bridged mono connection.
The inputs shall be located on the rear panel, and shall consist of a 3-pin detachable terminal block and a 3-pin XLR connector for each channel. The XLR input shall be wired with pin 2 high. Inputs shall be electronically balanced, with a minimum impedance of 12 kilohms balanced and 6 kilohms unbalanced, and a common mode rejection of at least 50 dB from 20 Hz to 20 kHz.
For each pair of sequentially numbered channels, a high-density 15-pin DataPort connector shall be provided for carrying both audio and amplifier operational status signals to and from a QSControl network. The DataPort shall also accommodate plug-in crossover filters and other such accessories.
Also for each sequentially numbered channel pair, a set of DIP switches shall be provided on the rear panel for: setting bridged mono and parallel-input operation; selecting clip limiters; and selecting high-pass filters and setting their frequencies.
Each channel shall be capable of meeting the following performance criteria with all channels driven: Sine-wave output power of 170 watts into 8 ohms, 20 Hz to 20 kHz at <0.03% THD; 250 watts into 4 ohms, 20 Hz to 20 kHz at <0.03% THD; and 450 watts into 2 ohms, 1 kHz at <1.0% THD. Frequency response (with filters not engaged) at 3 dB below rated power shall be 20 Hz to 20 kHz ±0.2 dB. The voltage gain shall be 29.0x, equivalent to 29.0 dB, and the input sensitivity shall be 1.28 Vrms (+4.4 dBu). The unweighted signal to noise ratio over the range of 20 Hz to 20 kHz shall exceed 106 dB, referenced to full output. IHF damping factor shall exceed 500.
The amplifier chassis shall occupy two rack spaces and have provisions for securing the rear corners. Depth from mounting surface to tips of rear supports shall be 14 in. (35.6 cm). The amplifier’s weight shall not exceed 21.0 lb. (9.5 kg).
The amplifier shall be the QSC Audio Products CX254.
230V Model
The amplifier shall contain all solid-state circuitry, using complementary silicon output devices. The amplifier shall operate from 50–60 Hz AC power and shall draw VA or less when driven with random program material at 1/8 of rated power into 4-ohm loads. The amplifier shall have a 320-C19 16A IEC mains connector and shall be equipped with a removable power cord having a standard Schuko (CEE 7/7) AC plug. The amplifier shall operate safely from a 230V AC outlet, and shall comply with FCC part 15 Class B requirements.
The amplifier shall have internal heat sinks cooled by forced air, driven by a 24-volt DC fan whose speed shall vary in response to heat sink temperatures to minimize acoustic noise. The fan's speed shall be controlled by a drive voltage ranging from approximately 9 volts when cool to approximately 24 volts when at the upper ranges of its operating temperature. Air flow shall be from rear to front to avoid temperature rise inside equipment racks; rack mounting of multiple amplifiers shall be possible without clearance for ventilation. The amplifier shall be capable of continuous operation at 1/3 of rated power into 4-ohm loads, in ambient temperatures up to 104° F (40° C).
The amplifier shall contain four independent amplifier channels powered by a low-impedance switching power supply. All amplifier protection systems shall be synchronized and self-resetting upon removal of fault. Each channel shall have circuitry to protect against short circuits or mismatched loads. Each channel shall independently monitor heat sink temperature and shall trigger fan speed boost, and if necessary, signal muting to prevent excessive temperature rise. Both channels shall have synchronized on-off muting, acting for three seconds after turn-on, and within ¼ second after turn-off or loss of AC power. Each channel shall have DC fault protection for the load, consisting of a shutdown of the power supply. Each channel shall have an independent and defeatable clip limiter and a 12 dB per octave high-pass filter. The corner frequency of the filter shall be selectable between 33 Hz and 75 Hz.
The front panel shall contain these features: an AC power switch; LED status indicators for power (green), bridged mono (yellow), and parallel inputs (yellow); independent LED output metering indicators for each channel for signal present or –30 dB (green), -20 dB (green), -10 dB (green), and clip (red); and a recessed, detented gain control for each channel with 21 attenuation settings. From 0 to 14 dB, the attenuation steps shall be 1-dB increments. The labeled attenuation settings shall be 0, 2, 4, 6, 8, 10, 12, 14, 18, 24, and ∞ dB. The 0 dB attenuation settings shall also be labeled with the amplifier’s equivalent voltage gain in dB. A removable security panel shall be provided for covering and preventing unauthorized access to the gain controls, when needed.
The output connectors for all channels shall be barrier strips located on the rear panel, with screw terminals and a safety shroud. One barrier strip shall be used for channels 1 and 2, and the other for channels 3 and 4. The terminals shall be arranged to facilitate bridged mono connection.
The inputs shall be located on the rear panel, and shall consist of a 3-pin detachable terminal block and a 3-pin XLR connector for each channel. The XLR input shall be wired with pin 2 high. Inputs shall be electronically balanced, with a minimum impedance of 12 kilohms balanced and 6 kilohms unbalanced, and a common mode rejection of at least 50 dB from 20 Hz to 20 kHz.
For each pair of sequentially numbered channels, a high-density 15-pin DataPort connector shall be provided for carrying both audio and amplifier operational status signals to and from a QSControl network. The DataPort shall also accommodate plug-in crossover filters and other such accessories.
Also for each sequentially numbered channel pair, a set of DIP switches shall be provided on the rear panel for: setting bridged mono and parallel-input operation; selecting clip limiters; and selecting high-pass filters and setting their frequencies.
Each channel shall be capable of meeting the following performance criteria with all channels driven: Sine-wave output power of 170 watts into 8 ohms, 20 Hz to 20 kHz at <0.03% THD; 250 watts into 4 ohms, 20 Hz to 20 kHz at <0.03% THD; and 450 watts into 2 ohms, 1 kHz at <1.0% THD. Frequency response (with filters not engaged) at 3 dB below rated power shall be 20 Hz to 20 kHz ±0.2 dB. The voltage gain shall be 29.0x, equivalent to 29.0 dB, and the input sensitivity shall be 1.28 Vrms (+4.4 dBu). The unweighted signal to noise ratio over the range of 20 Hz to 20 kHz shall exceed 106 dB, referenced to full output. IHF damping factor shall exceed 500.
The amplifier chassis shall occupy two rack spaces and have provisions for securing the rear corners. Depth from mounting surface to tips of rear supports shall be 14 in. (35.6 cm). The amplifier’s weight shall not exceed 21.0 lb. (9.5 kg).
The amplifier shall be the QSC Audio Products CX254.